LED lighting has an advantage such as lower power consumption, a longer service life, and a faster response time as compared to a conventional incandescent lamp and a fluorescent lamp, and its use spreads rapidly with a decline of product prices to broaden its application, in addition to indoor lighting, to various fields such as backlighting of a liquid crystal display (LCD) television and a LCD monitor and automotive lighting.
Since an LED itself is a semiconductor, a light emitting element itself has a long service life when used under specified operating conditions, but a resin material covering a light emitting element is likely to thermally degrade and readily loses clarity with heat generated, leading to make it unsuitable for use. Further, LEDs are also produced in a various forms of packages after taking into account luminescence properties and heat dissipation, but various approaches such as a space saving design and a forming method have to take into account when used in a limited space.
As a response to the problem related to heat generation, lamination of a heat sink plate to FPC has been proposed for improving heat release, while alignment of an LED on an FPC board has been proposed for space saving (Patent Literature 1).
As a lighting device it has been proposed to make complex fabrication of a circuit board mounted with an LED followed by three-dimensional molding (Patent Literature 2).